This application is a 371 of PCT/EP98/05388, filed Aug. 25, 1998.
The present invention relates to a method of protecting plants against attack by nematodes which comprises applying an effective amount to the plants, to parts of the plants and/or to the locus of the plants a compound having plant immunizing properties.
It is known that compounds having plant immunizing properties in general activate the plant""s own latent defence system against pathogenic microbial influences and accordingly are able to protect the plant against pathogenic microorganism such as bacteria and fungi. Such compounds are for example isonicotinic acid-derivatives (U.S. Pat. No. 4,968,344), benzo-1,2,3-thiadiazole-derivatives (U.S. Pat. No. 5,190,928), pyrido-1,2,3-thiadiazole-derivatives (U.S. Pat. No. 5,616,590) and thieno-1,2,3-thiadiazole-derivatives (EP-A-780,394). Benzoisothiazole-derivatives with nematicidal activities, but having no plant immunizing properties have been disclosed in U.S. Pat. No. 5,447,945.
Surprisingly it has now been found that compounds with plant immunizing properties effectively protect plants against attack by nematodes of various species and therefore are suitable for practical agricultural purposes, e.g. for protecting crop plants against attack by nematodes.
Particularly suitable for this purpose are benzo-1 ,2,3-thiadiazole-derivatives of formula I 
Within this group of compounds, it is believed that the active principle is the compound of formula I, wherein Z is COOH, i.e. 1,2,3-benzothiazole-7-carboxylic acid or its salt. Accordingly, all the compounds of formula I, wherein Z is a group which may undergo conversion to the carboxylic group, be it in the plant, on the plant or in the soil, are encompassed by this invention; particularly compounds of formula I, wherein Z is a C1 group to which there are bonded 1-3 halogen atoms or 1-3 substituted or unsubstituted hetero atoms O, S and/or N, in free form or in salt form.
Examples are benzo-1,2,3-thiadiazole carboxylic acid and its derivatives, like -carboxylic esters, -orthoesters, -thioesters, -amides, -thioamides, -iminoethers, -amidines, -imidic acids, -hydroxamic acids and trihalomethyl.
Of the compounds of formula I, preference is given to those wherein
Z is CN, COOH or a salt thereof, COxe2x80x94OC1-C6alkyl or COxe2x80x94SC1-C6alkyl, CSxe2x80x94OC1-C6alkyl, COxe2x80x94NHC1-C6alkyl, COxe2x80x94N(C1-C6alkyl)2, or CSxe2x80x94SC1-C6alkyl;
particularly preferred are compounds, wherein
Z is COOH or a salt thereof, CN, COOCH3 or most preferably COSCH3.
Preferred salts are alkali metal and alkaline earth metal salts, especially lithium, sodium, potassium, magnesium or calcium salts, and also organic salts, especially salts of salt-forming amines, for example trimethylamine, triethylamine, N,N-dimethylaniline, pyridine, triethanolamine, morpholine.
The method according to the invention is distinguished by an effective control of soil nematodes, is well tolerated by plants and environmentally friendly and, due to the low toxicity of the compounds, safe for users. Nematodes the attack of which to crop plants is controlled by the method according to the invention are soil nematodes that parasitise roots, for example nematodes of the genera Heterodera and Globodera (cystogenic nematodes), Meloidogyne (root-knot nematodes), Radopholus, Pratylenchus, Tylenchulus, Longidorus, Trichodorus, Xiphinema, Ditylenchus (stem parasites), Aphelenchoides (leaf nematodes), and Anguina (blossom nematodes). The method is particularly suitable against the attack of particularly harmful nematode species of the genus Meloidogyne, for example Meloidogyne incognita, and of the genus Heterodera, for example Heterodera glycines (soybean cyst nematode).
Target crops for the areas of indication disclosed herein comprise within the scope of the present invention e.g. the following species of plants: cereals (wheat, barley, rye, oats, rice, sorghum and related crops); beet (sugar beet and fodder beet); pomes, stone fruit and soft fruit (apples, pears, plums, peaches, almonds, cherries, strawberries, raspberries and blackberries); leguminous plants (beans, lentils, peas, soybeans); oil plants (rape, mustard, poppy, olives, sunflowers, coconut, castor oil plants, cocoa beans, groundnuts); cucumber.
Suitable carriers and adjuvants can be solid or liquid and are the substances ordinarily employed in formulation technology, e.g. natural or regenerated mineral substances, solvents, dispersants, wetting agents, tackifiers, thickeners, binders or fertilisers. Advantageous rates of application of the active ingredient mixture are normally from 0.1 to 10 kg of active ingredient (a.i.) per hectare, preferably from 100 g to 1000 g a.i./ha, especially from 250 g to 700 g a.i./ha. In the case of the treatment of seed, the rates of application are from 0.5 g to 1000 g, preferably from 5 g to 100 g, a.i. per 100 kg of seed. The formulations are prepared in known manner, e.g. by homogeneously mixing and/or grinding the active ingredients with extenders, e.g. solvents, solid carriers and surfactants. Suitable solvents are: aromatic hydrocarbons, preferably the fractions containing 8 to 12 carbon atoms, e.g. xylene mixtures or substituted naphthalenes, phthalates, such as dibutyl phthalate or dioctyl phthalate, aliphatic hydrocarbons, such as cyclohexane or paraffins, alcohols and glycols and their ethers and esters, such as ethanol, ethylene glycol, ethylene glycol monomethyl or monoethyl ether, ketones, such as cyclohexanone, strongly polar solvents, such as N-methyl-2-pyrrolidone, dimethyl sulfoxide or dimethylformamide, as well as vegetable oils or epoxidised vegetable oils, such as epoxidised coconut oil or soybean oil; or water. The solid carriers used, e.g. for dusts and dispersible powders, are normally natural mineral fillers, such as calcite, talcum, kaolin, montmorillonite or attapulgite. In order to improve the physical properties it is also possible to add highly dispersed silicic acid or highly dispersed absorbent polymers. Suitable granulated adsorptive carriers are porous types, for example pumice, broken brick, sepiolite or bentonite, and suitable nonsorbent carriers are, for example, calcite or sand. In addition, a great number of pregranulated materials of inorganic or organic nature can be used, e.g. especially dolomite or pulverised plant residues.
Depending upon the nature of the active ingredient to be formulated, suitable surface-active compounds are non-ionic, cationic and/or anionic surfactants having good emulsifying, dispersing and wetting properties. Particularly advantageous application-promoting adjuvants are also natural or synthetic phospholipids of the cephalin and lecithin series, e.g. phosphatidylethanolamine, phosphatidylserine, phosphatidylglycerol and lysolecithin. plants (marrows, cucumber, melons); fibre plants (cotton, flax, hemp, jute); citrus fruit (oranges, lemons, grapefruit, mandarins); vegetables (spinach, lettuce, asparagus, cabbages, carrots, onions, tomatoes, potatoes, paprika); lauraceae (avocados, cinnamon, camphor); or plants such as maize, tobacco, nuts, coffee, sugar cane, tea, vines, hops, bananas and natural rubber plants, as well as ornamentals (flowers, shrubs, broad-leaved trees and evergreens, such as conifers). This list does not represent any limitation. The method of the invention is particularly suitable for treating vegetables as tomatoes, soybean, carrots, potatoes and beet, as well as citrus fruit, vines, tobacco, mango and bananas.
A preferred method of applying the active ingredient is application to the parts of the plants that are above the soil, especially to the leaves (foliar application). The frequency and rate of application depend upon the biological and climatic living conditions of the pathogen. The active ingredients can, however, also penetrate the plant through the roots via the soil or via the water (systemic action) if the locus of the plant is impregnated with a liquid formulation (e.g. in rice culture) or if the substances are introduced in solid form into the soil, e.g. in the form of granules (soil application). In order to treat seed, the compounds can also be applied to the seeds (coating), either by impregnating the tubers or grains with a liquid formulation, or by coating them with an already combined wet or dry formulation. In addition, in special cases, other methods of application to plants are possible, for example treatment directed at the buds or the fruit trusses. The compounds of formula I may be applied together with further active ingredients, for example, insecticides, fungicides, bactericides, nematicides, molluscicides or other plant activators. Combinations with other nematicides may exhibit synergistic effects.
The compounds of the invention are generally used in form of a composition together with the adjuvants conventionally employed in formulation technology. They are formulated in known manner e.g. into emulsifiable concentrates, directly sprayable or dilutable solutions, dilute emulsions, wettable powders, soluble powders, dusts, granules, and also encapsulations in e.g. polymer substances. As with the nature of the compositions, the methods of application, such as spraying, dusting, scattering or pouring, are chosen in accordance with the intended objectives and the prevailing circumstances.
The compositions generally comprise 0.1 to 99%, preferably 0.1 to 95%, of active ingredients, 99.9 to 1%, preferably 99.9 to 5%, of a solid or liquid adjuvant and 0 to 25%, preferably 0.1 to 25%, of a surfactant.
Whereas commercial products will preferably be formulated as concentrates, the end user will normally employ dilute formulations.